Lung and bladder cancer in a Norwegian municipality with iron and steel producing industry: population based case-control studies

Our plain-English summary of Lung and bladder cancer in a Norwegian municipality with iron and steel producing industry: population based case-control studies, by T.K. Grimsrud, H. Langseth, A. Engeland, et al (Occupational and Environmental Medicine, 1998).

The study

• Authors: T.K. Grimsrud, H. Langseth, A. Engeland, A. Andersen
• Journal: Occupational and Environmental Medicine
• Published: 1998;55(6):387-92
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: To investigate the influence of occupation on the rising incidence of lung and bladder cancer among men in a Norwegian municipality where an iron and steel plant constituted the key industry between 1955 and 1989.

Methods: Based on the lung cancer cases reported to the Cancer Registry of Norway from 1980 to 1992 a population based case-control study was performed, including 86 cases and 196 controls. Information on occupations and smoking habits was collected through interviews and from the personnel files from the industrial plants. A case-control study on bladder cancer with 52 cases and 156 controls was carried out to cast light on the role of polycyclic aromatic hydrocarbons (PAHs).

Results: An odds ratio (OR) for lung cancer of 2.9 (95% confidence interval (95% CI) 1.2 to 6.7) was associated with exposure to PAHs. Based on data from personnel files, increased risk of lung cancer (OR 2.8 95% CI 1.1 to 7.0) was associated with work experience in the pig iron department at the ironworks. A non-significant OR of 1.8 was associated with exposure to asbestos. Bladder cancer was not associated with exposure to PAHs at the iron, steel, and coke plant, or with experience from any of the production departments at the plant.

Conclusions: One fifth of the lung cancer cases were attributed to exposure to PAHs or asbestos. More than 80% of the cases of lung cancer were attributed to tobacco smoking. The cancer risk in the pig iron department may be due to a combination of exposures to PAH, asbestos, or dust of mixed composition.

In plain English

The authors studied men in Rana, a municipality in northern Norway where an iron and steel plant was the main industry from 1955 to the late 1980s. They ran two case-control studies of men diagnosed from 1980 to 1992. The lung cancer study had 86 cases and 196 controls and used interviews and plant personnel files. The bladder cancer study had 52 cases, three controls per case, and used personnel files only. Asbestos exposure was assigned by job, such as work in the plant's mason department, maintenance work, or certain jobs elsewhere. No fiber type was named. After adjusting for smoking, the odds ratio for lung cancer was 1.8 (95% CI 0.7 to 4.6) for asbestos, which was not statistically significant. It was 2.9 (95% CI 1.2 to 6.7) for polycyclic aromatic hydrocarbons (PAHs). Pig iron department work had an odds ratio of 2.8 (95% CI 1.1 to 7.0) compared with little or no plant work. Bladder cancer was not linked to PAH exposure at the plant. The authors attributed 21% of lung cancer cases to PAHs, asbestos, or both, and 83% to smoking. Relatives answered for most lung cancer cases.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Two population based case-control studies (lung cancer and bladder cancer), analysed with conditional logistic regression
• Who was studied: Male residents of the municipality of Rana, northern Norway, diagnosed 1 January 1980 to 31 December 1992. Lung cancer study: 88 cases identified, of whom 86 cases and 196 matched population controls were analysed. Bladder cancer study: all 52 incident cases, with three controls drawn per case
• Exposure: Asbestos and polycyclic aromatic hydrocarbons (PAHs), assigned by job and department from interviews and personnel files. Asbestos exposure was assigned to work in the mason department or maintenance in heat-producing departments of the iron and steel plant, and to outside jobs such as plumber, stoker, or shipyard welder or fitter. No asbestos fiber type is specified
• Main results:
  • Lung cancer, asbestos-exposed men: smoking-adjusted odds ratio 1.8 (95% CI 0.7 to 4.6), based on 13 cases and 18 controls. This was not statistically significant
  • Lung cancer, PAH-exposed men: smoking-adjusted odds ratio 2.9 (95% CI 1.2 to 6.7)
  • A possible interaction between asbestos and PAH exposure on lung cancer was tested and was not statistically significant
  • Lung cancer, iron and steel workers with experience in the pig iron department: odds ratio 2.8 (95% CI 1.1 to 7.0) compared with men with no or negligible employment at the plant
  • For lung cancer, the risk linked to asbestos or PAH exposure outside the iron, steel, and coke plant was more pronounced than the risk from exposure within the plant, but the difference was not statistically significant
  • Bladder cancer: no sign of increased risk with PAH exposure within the iron, steel, and coke plant
  • The population attributable risk of lung cancer for PAHs, asbestos, or both was 21%, adjusted for smoking
  • The population attributable risk of lung cancer for smoking was 83%, adjusted for occupational exposures
• The authors' conclusion: The authors concluded that the personnel files identified a cancer risk in the pig iron department, probably associated with PAHs, and that exposure to asbestos or silica-containing dust may have contributed
• Limitations the authors state:
  • Cases and controls differed in who answered the interview. Only 7 of 86 lung cancer cases answered for themselves, compared with 151 of 196 controls. The authors said this could cause differential misclassification
  • Nearly 25% of controls refused to be interviewed
  • The study design is vulnerable to migration in and out of the municipality
  • Some plant workers lived in neighbouring municipalities, which could mean lost cases and a reduced chance of finding an industrial risk
  • The job exposure matrix may have misclassified exposure or left out important exposures
  • The bladder cancer study had no information on smoking or on jobs outside the plant
  • The bladder cancer finding might change with longer observation time

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Cancer Registry, Case-Control Study, Habit, Odds Ratio, confidence interval.

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